Oil well apparatus



April 1, 1958 R. R WATERMAN 2,828,821

on. WELL APPARATUS Filed Feb. 5, 1954 Sheets-Sheet 1 -/50 lb. GayePressure 366E STEAM v 550 lb. er .40, z LINE I i fl z ass-n H v i A .24;-10 32 DEPTH O I WELL (ABOVE FL u/o LEVEL I 1 3;

a; z 19- 24 l -7}=-300'F. HEATING SECTION RUSSELL mwArmm/v, CONDE vs. IINVENTOR. cm m" HUEBNE'RsBEEHLL-R,

WORREL & HERZ/G, CLEARANCE By ATTORNEYS.

April 1, 1958 Filed Feb. 3, 1954 R. R- WATERMAN OIL WELL APPARATUS 3Sheets-Sheet 3 R. WA 7' ERMAN;

RUSSELL IN VEN TOR.

HUEBNER,BEEHLER,

WORREL A r TORNE vs.

United States Patent OIL WELL APPARATUS Russell R. Waterman, Long Beach,Calif. Application February 3, 1954, Serial No. 497,860

' 4 Claims. (Cl. 166-57) The application has reference to a method andapparatus for the production of crude petroleum from wells. Thisapplication is a continuation-in-part of applicants copendingapplication Serial No. 170,116, filed June 24, 1950, now Patent No.2,705,535.

More particularly the application is one directed to increasing the flowof oil wells by sending steam under pressure into a heating jacket inthe well at the portion of the well to be heated, and there utilizingthe major portion of heat in the steam in order to raise the temperatureof the crude petroleum before it is pumped, making it flow more readilythrough the pump line.

It has long been appreciated that wells for the production of crudepetroleum can be made to flow faster when the wells are heated. For morethan fifty years a great variety of types of apparatus have been devisedwith the intention of carrying heat deep into oil wells. Some of theseapparatus involve a recirculating system so that condensate from thesteam as it gives up its heat is returned through a separate pipe lineto the surface, presumably to save condensate and also possibly to avoidinjecting steam into the production. Such systems have been found to beconsiderably more expensive than the amount of increase in productionhas warranted. Furthermore, the recirculating system necessitates aspecial pump for the condensate lifting an ever increasing head ofcondensate as the system is lowered into deeper wells. Moreover,recirculating systems necessitate two pipes in a well in addition to thepump line and tend to fill the wells with piping to the extent that thesystem cannot be worked in casings of small diameter. An added and verymaterial objection is that the major portion of the steam tends to heatthe returning condensate and the production as it nears the surface tosuch an extent that in wells of any appreciable depth there is no steamat the lower levels where the heating is most desirable and thetemperature of condensate at those levels is not sufiiciently high tomaterially increase the production of the petroleum.

Other attempts have been made to employ non-recirculating systems, andin such systems there have been included safety release valves orpop-oil valves to release steam pressure after a previous build-up inpressure, presumably in an effort to raise the temperature in the steamline. The last-identified systems have had the marked disadvantage ofdischarging live steam into the well, causing emulsification of thecrude petroleum to such an extent that systems of this kind have neveroperated successfully and have never been employed on a commercialscale.

Among the objects of the invention is to provide a new and improvedmethod and apparatus for heating oil wells and particularly for heatingselected portions of the oil well where the production can be benefittedmost by application of heat at a relatively high temperature. v

Another object of the invention is to provide a new and improved methodand apparatus for heating oil wells so hat heat can be applied over theentire depth of producing sand or strata at a relatively uniform ratethroughout the depth or thickness of the strata.

Another object of the invention is to provide a new and improved methodand apparatus for heating oil wells wherein the quantity of steamsupplied and the amount of heat generated can be carefully andaccurately regulated so that a maximum amount of heat may be imparted tothe crude petroleum while at the same time overheating can be avoided.

Another object still is to provide a new and improved method andapparatus for heating oil wells wherein the ap paratus is of such smalldiameter that it can be lowered into the well between the casing and thepump string without it being necessary to remove the pump string andthereby avoid stopping production for a length of time no greater thanthat necessary to lower the apparatus into the well. and to recap thecasing.

Still further among the objects of the invention is to provide a new andimproved method and apparatus for the practice of the method by means ofwhich the apparatus can be adjusted and fitted to agreat variety ofconditions as, for example, different depths below the surface,different production fluid levels, different heads of fluid at thebottom of wells and different heating requirements so that asubstantially maximum amount of heat can be applied specifically to thearea needing most to be heated. The objects include heating underconditions where substantially a precise control can be maintained atall times over the quantity of steam supplied at a selected advantageouspressure to the end that the method can be operated sufficientlyeconomically to warrant employment of the method and apparatus underconditions where the increase in fiow of crude petroleum over the normalpumping rate is as low as one hundred percent and lower.

Further included among the objects of the invention is to provide a newand improved method and apparatus wherein steam under pressure can beintroduced'into oil wells by use of an apparatus of substantially smallexterior diameter uniform throughout its length so that it can be raisedor lowered to ditterent levels as occasion may require and furtherwherein an accurate control is included in the heating section readilyvariable as different conditions are encountered and further whereinsufficient control is exercised over condensate emitted from the heatingsection so that no live steam is permitted to escape into the well. Y

With these and other objects in view, the invention consists in theconstruction, arrangement and combination of the various parts of thedevice whereby the objects contemplated are attained, as hereinafter setforth, pointed out in the appended claims and illustrated in theaccompanying drawings.

In the drawings:

Figure 1 is a schematic representation ofan oil well with the apparatusinstalled therein.

Figure 2 is a longitudinally sectioned foreshortened view of an oil wellshowing the relative location of the heating apparatus to the casing,the liner, and a pump string.

Figure 2A is a fragmentary vertical sectional view of an oil wellshowing an insulated steam line.

Figure 3 is a longitudinal sectional foreshortened view of the heatingand condensing sections of the apparatus- Figure 4 is a longitudinalsectional viewof the lower portion of the condensing section normallyfitting at the lower end of Figure 3.

Figure 5 is a graph showing steam pressure variations encountered as theheating process is applied and the rate of steam supplied in accordancewith a time scale.

In the schematic view of Figure 1 there is illustrated an oil wellcomprising a casing 10 and a liner 11. The ground surface is indicatedat 12 and the bottom of the well at 13. A pump string 14 is representedas extending into the well to a location 15 adjacent the bottom 13 ofthe well but sufiiciently above the bottoin'to be certain of pumpingrelatively clean crude petroleum. The well is capped in a conventionalmanner by employment asaaeer 3. of the customary cap 16. As furtherindicated the nortrial 'free level of crude petroleum in the bottom ofthe well is at 17 whereas the production fluid level when the pump is inoperation is at 18. Heat is supplied to the well by means of a steamsupply line 19 which takes steam from a conventional boiler, not shown,from which a section 29 of the steam line connects to a pressureregulator21 having a gauge 22 on the supply side and a gauge 23 on theopposite side to which the supply/"line 19 is connected.

At the lower end of the steam supply line 19 is a heating section 24, atthe lower end of which is a condensing section 25.v It will be'notedthat the lower end of the condensing section 25 is "at a short distanceabove the bottom 13 of the well, thereby leaving a slight clearance. Thetop of' the heating section is normally about at the height of theproduction fluid level 18. In the well schematically illustrated thebottom of the well will have a somewhat shallow sump 26 ordinarilyfilled with sludge above which is a depth of production fiuid 27 whichwill be determined by the particular character of the well in question.It is a reservoir of crude'petroleum which is supplied by inflow of thepetroleum from the surrounding strata to a depth determined by theparticular level and character of the strata. Above the production fluidlevel when the pump is operating is a space 28 normally filled with amixture of air and gas and perhaps some water vapor held within thecasing by means of the cap 16.

' The heating apparatus is shown in somewhat greater detail in Figures2, 3 and 4. The steam supply line 19, which in most instances may be al-inch to l -inch pipe, is customarily put together in the usual 20-footlengths by employment of exterior couplings 30. A packing gland 31 ofthe customary variety may be provided at the cap or well head 16. At thelower end of the steam supply line 19 the heating section 24 isconnected by means of an adapter 32. For illustrative purposes in Figure2 the heating section is shown as of larger exterior diameter than thesteam supply line, this circumstance being more particularly prevalentwhen a 1-inch steam supply line is employed with a l -inch heatingsection. Circumstances, however, may arise wherein the steam supply linemay also be a usual line.

As is more readily seenin Figure 3, the heating section 24 includes anumber of sections 24 of the customary conventional length at the upperend of which is a flush tool joint 33. At the upper end of the flushtool joint are internal threads 34 adapted to engage external threads 35of the adapter 32. At the lower end of each heating section pipe 24' isa male flush tool joint 36 having external threads 37 at the lower endadapted to engage the internal threads 34 on the next lower female flushtool joint 33.

The flush tool joints in each case are pressed into the end of the pipeand sealed therein'by welds 38. As many lengths 24' of the heatingsection pipe may be joined together as conditions warrant. The series oflengms 24, 24", etc., comprising the heating section provide an interiorpassage .or chamber 39.

.At the lowermost end of the heating section there is attached anorifice body 40. The orifice body is provided with interior threads 41adapted 'to engage the exterior threads 45 of the immediately adjacentflush tool joint 36. Extending through the orifice body is a borecomprising a larger section at the threads 41 joining a smaller section42, there being provided interior threads 44 at the upper end of thesmaller section. An orifice block 45 slides into the smaller section toa position limited by a shoulder 46. A strainer 47 threadedly engagesthe threads 44 and serves as a means of holding the orifice blockinplace. The exterior diameter of the strainer is smaller than a bore 48through the adjacent flush tool joint so that the strainer may he slideasily thereinto.

An orifice passage 4 extends axially through the upper end of theorifice block and is of smaller diameter than an outflow passage 50therein. Holes 51 of the strainer are smaller in diameter than thediameter of the orifice passage 49. At the bottom and forming part ofthe orifice block is a turbulator indicated generally by the referencecharacter 52. Extending through the turbu lator is an axial turbulatorpassage 54 intersected at its lower end by a transverse turbulatorpassage 55 so that the turbulator passage abruptly changes directionfrom axial to transverse before communicating with a passage 56 in thetool joint 33.

The condensing section 25 is attached to the tool joint 33 andcustomarily need be but a single pipe length of the usual 20 feet. Atthe lower end of the condensing section is a pilot body 57 having apoint 58 to facilitate guiding it into the casing. The pilot body hastherein a valve chamber 59 housing a ball 60 urged by a spring 61normally into seating engagement with a corner 62 serving as a valveseat. The valve chamber 59 communicates laterally by means of out-flowpassages 63 with the interior of the liner 11. By this device acondensing passage 64 serves as a communication medium between theorifice and the interior of the well at the area of the liner. The ballcheck 6:? serves as a means of preventing inflow of any fluid in thewell while the apparatus is being lowered into place.

In Figure 2A the steam line 19 is shown covered with a heat insulatingcoating 19' of some suitable material. This is especially desirable toreduce condensation of steam on the way down when wells of greater depthare to be heated.

It will be noted from the foregoing description that the steam line, theheating section, and the condensing section are in axial alignment andof such comparatively small diameter that they are readily containedwithin the casingand also the liner between the wall of the liner andthe pump line 14. Steam passed to the steam supply line 19 travelsdownwardly through the steam line to the heating section which, in theexample chosen, has a chamber of slightly greater interior diameter thanthe interior diameter of the supply line. At the lower end of theheating section the orifice passage 4% provides a definitely controlledrestricting orifice from which condensed steam in the form of water isforced outwardly at a rate of flow scarcely more than sufficient to passall of the water which has been changed into condensate as the heat ofthe steam is given up. The heating section therefore forms a heatingjacket wherein the steam under pressure is carefully controlled byoperation of the orifice so that a major amount of its heat is given upin the area desired.

' As the condensate emerges from the orifice passage, it enters theturbulator through the axial turbulator passage 54 and then changesdirection as it emerges through the transverse turbulator passages 55.In the event there may be some slight amount of steam with the ejectedcondensate, the steam will be first also to change direction impingingupon the interior wall of the passage 56 and will condense within thecondensing passage 64 before it finally passes the ball check valve 61'}on its way through the outflow passage 63 to the interior of the oilwell.

Inasmuch as the orifice passage or orifice opening is an importantelement to the successful operation of, the method and apparatus, thesize of the orifice passage must be determined in accordance with theseveral factors involved in-a particular installation. It is essentialthat s orifice opening and the pressure of steam from the supply line.Consequently, although as an ideal condition, all the condensate must beejected and no steam ejected therewith, under practical conditions ofoperation there will be some steam behind the ejection of condensate tothe extent that a slight amount of steam will be passed with thecondensate. The quantity of steam, however, must be kept to a minimum,below the ability of the condensing section to condense in order that nolive steam be ejected into the well.

Among the varying conditions which influence the size of the orifice arethe depth of the well, the head of liquid in the heating section, thesize of the steam supply line and size of the heating section, thetemperature of the crude petroleum below the production fluid level, andalso the temperature of the well above the fluid level. It isaccordingly necessary to provide an orifice which will meet theconditions in a given installation but for practical reasons an orificeshould be selected which will perform satisfactorily under an assortmentof conditions which may vary to a small degree between one installationand another, it being keptin mind that the steam pressure may be variedunder different conditions so that an orifice of the same size may bemade to function properly in one of several diiferent types ofinstallations within reasonable limits.

By way of example and with reference to the schematic diagram of Figure1, a set of conditions may be assumed in order to illustrate thedetermination of the proper size restricting orifice passage in theorifice block. For example, let it be assumed that the depth of the Wellbetween the surface 12 and the bottom 13 is 2000 feet. In the well undera given set of conditions the free fluid level is 112 feet and that whenunder pump the production fluid level is 100 feet.

Let it further be assumed that the lower end of the pump line is setabove the very bottom of the well by a distance of feet in order to makecertain that only clear crude petroleum is being pumped. It will beadvisable under those same circumstances to have the pilot body 57 setat approximately the same clearance above the extreme bottom 13 of thewell.

Under these conditions a steam plant may be set to deliver 550 poundsper hour of steam at 150 pounds gauge pressure and at a temperature of366 F. The temperature and pressure figures given are temperature andpressure figures at the surface 12, namely, at the top of the well.

For the conditions mentioned the depth of the well above the productionfluidlevel is 1,900 feet. Consequently, there will be a pressure drop inthe steam supply line throughout this 1,900 feet of travel in a l-inchpipe where a 1-inch pipe has been selected for the steam supply line.From steam tables the pressure drop will be found to be 96 pounds forthe 1-inch pipe for the distance selected in the example.

Let it be assumed futher that temperature T has been found to be 200 F.T is 360 F. From steam tables the ratio of heat transfer between a steampressure line and a surrounding gaseous body may be taken as 2. Withthese figures as a basis the condensation in the 1,900 foot drop ofsteam from the surface to the production fluid level will be found to be195 pounds per hour. This of course is an approximate figure butaccurate to the extent that steam calculations are made. Thecondensation will also be found to be equal to or slightly greater than6 /2 horsepower.

In addition to the amount of condensate accumulating in the steam supplyline there will also be a greater proportion of condensate forming inthe heating section. Since the heating section is in a liquid bath, theheat transfer ratio can be taken as 110. The temperature of the liquidbath, namely, the crude petroleum liquid at the bottom of the well, uponmeasurement is assumed to be 150 F.

- perature of the steam in the heating section, will be 300 F., therebeing a drop in temperature of 66 F.- between the surface and theproduction fluid level. Under the same set of conditions there will be adrop in gauge pressure to 54 pounds gauge at the production fluidlevel..

With a ratio of T to T at approximately 110, the condensation in theheating section will be found to be substantially 349 pounds per hour.When this is added to the 195 pounds per hour of condensation in thesteam line above the production fluid level, the total condensate forthese two sections of the apparatus will be found to equal 544 poundsper hour. This is the amount of liquid which must be passed by theorifice passage. Another factor which enters into the size of theorifice passage is the pressure behind the liquid condensate.

By further calculation in accordance with conventional thermo-dynamictables, the pressure drop between the production fluid level and thelocation of the orifice passage for the conditions herein selected willbe found to be 34 pounds. 34 pounds added to the 96 pound pressure dropin the steam line equals a total-pressure drop of 130 pounds. 130 poundssubtracted from the initial 150 pounds gauge pressure at the surfacegives 20 pounds of steam pressure at the orifice opening.

In the event insulation is employed on the steam line, the condensationoccurring in the steam line will need to be calculated, taking intoconsideration the different rate of transfer of heat laterally in theinsulated line.

From restricted orifice tables an orifice size will therefore beselected as one capable of passing 349 pounds per hour of water at apressure of 20 pounds. Since some slight variation in orifice size ispermitted, it will be practical to select the orifice size correspondingto a conventional drill size. Under the conditions herein selected byway of example a number 28 drill size will be found to produce anorifice opening closest to the calculated orifice opening for the 349pounds of water per hour at 20 pounds pressure. A number 28 drill isfoundfrom tables to be a drill having a diameter of .1405 inches. Underthose circumstances where, as previously indicated, a one inch pipe isused for the heating section, by calculation it will be found that thearea of a flow restricting orifice made with a number 28 drill asdescribed is about 1.8% of the cross sectional area of the interior ofthe one inch pipe. Should a 1% inch pipe be used for the heatingsection, the percentage would be proportionately less with the same sizeorifice. A change in the conditions with respect to temperature of crudepetroleum, temperness of the producing strata.

ature of the well, depth of the producing strata below the surface,etc., as already made reference to might suggest some variation in thesize of the orifice within the limits which have been found capable ofproducing satisfactory performance. Satisfactory performance isexperienced when the area of the orifice is from 1% to 15% of theheating section. The specific percentage will depend on variations inthe values given in the example.

When the apparatus is to be employed in accordance with, for example,the set of conditions given, the heating section is lowered into thewell after the condensing section. A sufiicient number of pipe lengthsare joined together forming the heating section so that the overalllength of the heating section is equal to the depth of production fluidat the bottom of the well. For installations where the producing stratamay be above the bottom of the well, the length of the entire heatingsection may be calculated so that it is long enough to span the entirethick- After .the'heating section has been lowered to the selectedpositiomthe steam supply line is fastened at that level and steam ispassed into the steam supply line. As an aid in understanding the actionof the apparatus in accordance with the practice of the method hereindisclosed, reference is made to the' graph of Figure 5. As there shownthe timein minutes issltown on the horizontal axis. Two vertical axesare employed, the one on the left showing steam in pounds per hour,andtlre vertical axis on the right showing presto in n nasper squareinch gauge. Under the asd conditions the graph of supply of steam at 555pounds 'per hour will be the straight horizontal line 70. The curve ofpressure will be a curve indicating a varying pressure namely, thecurved line 71.

A s steam is' supplied the pressure dilierential gauges 22am 23 willshow a very rapid pressure drop for about the first two minutes 'ofoperation until the pressure on the low side fof the pressuredifferential gauges, namely, the pressure in the steam supply line inthe Well builds ep c about lllllpounds gauge. Thereafter there will bea' continued build-up of pressure but at a diminishing rate until afterabout seven minutes the pressure in the well will reach about 140 to1-45 pounds gauge at the time the sears under pressurehits theproduction fluid level. Aft'er reaching that level, there will be agreater absorption o'filie'at from the steam and the pressure in the,steam line will diminish slightly until the heat Supplied star tobalance the heat absorbed, after an interval of about eleven minutesfollowing the start of the operation. Thereafter pressure will againbegin to build up gradually until after about sixteen to seventeenminutes of operation steam reaches the orifice. At that pointcthere willbe a sharp change in the registrations of the pressure ditferentialgauges showing that the steam pressure has reached 150 pounds per squareinch gauge. Where the steam is being supplied at the rate of 550 poundsper hour, the pressure will balance at 150 Pounds and continue on astraight line thereafter provided that an orifice of the proper size hasbeen selected.

If, for example, the orifice should be too small, the buildup inpressure will go above 150 pounds per square inch as indicated by thedotted curved line 72 of Figure 5. It will be appreciated from theforegoing explanation that the amount of heat supplied to aninstallation can be very carefully balanced at all times during itsoperation by supplying the proper amount of steam at the selectedpressure, which correct supply can be constantly checked by inspectionof the pressure differential gauges 22 and 23.

If it be found that the temperature of the crude petroleum being pumpedruns too high, the amount of steam can be reduced. On the contrary, ifit be found that the temperature of the crude petroleum being producedis lower than good pumping conditions will permit, the quantity of steamcan be increased in order to raise the temperature and thereby increasethe rate of production on the pump.

While the apparatus and method herein described has been foundparticularly advantageous in the production of 'low gravity crudepetroleum at moderately great depths up to about 3,500 feet, it has alsobeen found that the method and apparatus can also be used successfullyfor clearing wells wherein the paraifin content has been high by heatingthe areas impregnated with paraifin, thereby permitting wellsofrelatively high gravity to how freely at agreatly increased productionrate.

While I have herein'shown and described my invention in what I haveconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of myinvention, which is not to be limited to the details disclosed hereinbut is to be accorded the full scope of the claims so as to embrace anyand all equivalent methods and apparatus.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In an oil well including an oil accumulating space at thebottom ofthe well and a pump line in the well between said space and the surface,the combination of a bottom hole heater comprising a steam line forsteamunder pressure located between the pump line and the wall of thewell, an elongated heating jacket having a chamber therein, said heatingjacket being independent of the pump line and forming a downwardcontinuation of the steam line and being located between the pump lineand the wall of the well, said jacket having an upper connectionattached to said steam line, means forming a constantly open fiowrestricting hydraulic orifice passage of fixed diameter at the lower endof the chamber and extending downwardly therefrom, an outflow condensingline having a chamber therein and extending downwardly from the orificepassage at a location spaced from the pump line and between the pumpline and the wall of the well, and an unrestricted outlet opening at thelower end of the condensing passage.

2. In an oil well having a casing and liner assembly therein includingan oil accumulating space at the bottirn of the well and a pump line inthe casing between said space and the surface of the ground, thecombination of a bottom hole heater comprising a steam line, a heatingjacket and a condensing line attached generally in axial alignment inone continuous string and of substantially the same diameter, saiddiameter being smaller than the diameter of said pump line, said heatingjacket having a chamber therein and having a connection secured to thesteam line and extending axially downward from the lower end of thesteam line at a location separated from said pump line and between thewell casing and liner assembly and the pump line, means forming aconstantly openfiow-restricting hydraulic orifice passage openingaxially downwardly from the lower end of the chamber into the condensingline, means forming a condensing passage below the jacket and extendingaxially downwardly from the orifice passage and means forming anunrestricted outlet opening from the lower end of the condensing passageextending in a direction different from the longitudinal axis of thecondensing passage.

3. A'bottom hole heater for'an oil well having a pump line'therein andcomprising a steam line for steam under pressure and an elongatedheating jacket having a chamber of substantially the same diameter asthe steam line extending axially downwardly from the lower end of thesteam line, said jacket being independent of and spaced from the pumpline and being located between the .pump line and the wall of said well,means forming a constantly open restricted orifice passage openingaxially downwardly from the lower end or" the chamber, said orificepassage having a cross-sectional area equal to between about 2 /2 and 9/2% of the cross-sectional area of the chamber, a s'trainer at the inletside of the orifice passage and a discharge passage means of largercapacity than the orifice passage located below and extending axiallydownwardly therefrom, means forming a discharge port from the dischargepassage means and means forming a condensing passage located below andextending axially downwardly from'the discharge passage means, saidcondensing passage being at a location spaced from the pump line andbetween the pump line and the Wall of the well.

4. The bottom hole heater as defined in claim 3 wherein'said condensingpassage has an outlet opening from the lower end, an axially'imperiorate pilot body at the lower end of the condensing passage, saidoutlet opening having a portion thereof in the pilot body and extendinglaterally therewithin, and an outwardly open check valve in said outletopening.

References Cited in the file of this patent UNITED STATES PATENTS

